Random Fate

August 14, 2005

Lasers - the light is still fantastic

By Jack Grant

In an interesting case of similar advances being made almost simultaneously in two different places:

Quantum Cascade Lasers Key To Handheld Gas And Liquid Sensors
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Tiny Infrared Laser Holds Promise As Weapon Against Terror

A "quantum cascade laser" sounds like some kind of technobabble from Star Trek, but it is the real deal. However, unlike what we see on Star Trek or other television shows, sensors that can detect and identify an arbitrarily wide range of substances do not exist. Much of the development of chemistry in the early days even up until recently has been focused on the identification of unknown substances and ultimately, their molecular structure.

The parallel development discussed in the two articles linked above is in the area of lasers. Again, contrary to popular perception, a laser cannot be changed to any color you like, and the color, or wavelength, of the light coming out of the laser is important when the light is used in a detection system, because certain wavelengths are needed to detect certain chemicals. There are some lasers, such as dye lasers, that can be tuned to different wavelengths within a limited range, but these are large systems that are very awkward to deal with, including coping with toxic and carcinogenic materials that usually have to be pumped in a recirculating system so the dye does not overheat and degrade more quickly, and after all the effort involved the power of the resulting laser beam is very low.

A tunable laser that is small, portable, and powerful will be very important in developing sensors for many different materials, as is discussed in the articles above.

In another development involving lasers, this time in the field of biology, carbon nanotubes, a hot topic in solid state science for well over a decade, apparently can be modified to stick to cancer cells, creating a way for lasers to be used to literally burn the cancer out without affecting the normal cells surrounding the cancer:

Nanotube-Laser Combo Selectively Targets Cancer Cells, Study Shows

This is possible using a technique similar to the one used by the anti-cancer "smart bomb" recently announced, by adding certain chemical structures to the outsides of the molecule you want to attach to the cancer cell, like puzzle pieces those structures lock onto the corresponding structures that exist on the cancer cells but not healthy cells. The recent spate of developments in this field show the huge progress that has been made in chemical synthesis in the past few years.

In the chemical and biological engineering fields we may be benefiting from a similar acceleration to that seen over the last three decades in electronics. Each advance enables two or more other developments, which then provide the foundation for others, increasing the rate of technological progress at an almost exponential rate.

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